Active electronically scanned array (AESA) systems provide reliable performance over respective ultra-wide bands (UWBs) of operating frequencies. AESA systems are commonly used in communication systems, military and weather radar systems, electronic intelligence systems, or biological or medical microwave imaging systems. An AESA system makes use of an array of radiating elements (or antenna elements) steerable via a respective group of transmit/receive modules (TRMs). By independently steering each of its antenna elements, an AESA system provides a relatively high reception/transmission performance through constructive accumulation of signals associated with a plurality of antenna elements. Also, because of the inherent capability to simultaneously use, and independently steer, a respective plurality of antenna elements, the single failure of one or few antenna elements within an AESA system have little effect on the operation of the AESA system as the rest of the antenna elements can continue to function un-interrupted. Furthermore, AESA systems are difficult to jam because of their capability to hop from one operational frequency to another within the respective UWB.
The signal received/transmitted by an AESA antenna system is a combination of the signals received/transmitted by the respective antenna elements. As such, the power of the received/transmitted signal can increase with the number of antenna elements in the AESA system. Various applications call for larger electronically scanned array (ESA) systems, active or passive, to improve signal gain, reception sensitivity, and smaller beam width. As such, printed circuit boards (PCB) of ESA systems are becoming excessively large. However, manufacturing of large PCBs suffers from poor yield, therefore, driving up cost significantly. In particular, manufacturing large PCBs involves a relatively larger number of sequential laminations, which increases the likelihood of manufacturing deficiencies and leads to the poor yield.
Due to the poor yield associated with the fabrication of large PCBs, the demand for larger number of antenna elements in ESA systems may not be practically fulfilled using monolithic PCBs. Another alternative to construct large ESA systems is by tiling multiple smaller PCBs, each corresponding to a respective ESA sub-system, into a large ESA system. Multi-tile ESA systems are beneficial from a yield and cost standpoint. However, tiling PCBs presents various technical challenges with regard to the mechanical coupling of the PCBs without perturbing the electronic components of the respective ESA subsystems, with regard to the protection of the ESA sub-systems, or with regard to the performance of the resulting ESA system.
One common performance factor for antenna arrays is the distribution and strength of respective radiation pattern sidelobes. In particular, the sidelobes that are closest to the main lobe of an antenna array can contribute the most to signal interference. When designing antenna arrays, one of the goals is to reduce the number and the gain of the sidelobes.